Water Piston Engine

what do you know about water piston engine !! is there any online documents you provide me with , because I couldn't find anything online!!
I know it uses no cylinders and the thrust is generated by the water somehow!! I wish I can find something to read about the subject..
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Thanks you in advance

Are you referring to RAM water pumps? Look it up on internet. There are both commercial and DIY versions available. I used one many years ago. The only problem I had was occasionally finding small sticks (from the supply line) in one of the check valves. Use a screen on the input supply line.